Planar coils in which the coil windings are applied to the surface of a substrate are known per se from the prior art. Only a relatively low inductance can be achieved cost-efficiently with such planar coils, wherein the planar coils additionally take up a relatively large amount of space on the substrate surface.
Embedded Faltflex coils are known from www.elektroniknet.de, 26 Apr. 2012, “Embedding von aktiven and passive Bauteilen in die Leiterplatte” (“Embedding of active and passive components into the printed circuit board”). Here, flexible film structures are folded such that coils can be produced in any size with a practically arbitrary number of layers. This is particularly advantageous for sensor applications.
A coil structure for a printed circuit board arrangement is known from DE 43 06 416 A1. A winding of the coil is formed by metallized bores and conductive track portions. A ferrite core can be introduced laterally in a slit in the printed circuit board. Alternatively, the inner layers of the printed circuit board can be used directly as a support for imprinted core structures. A disadvantage with this coil structure is that on the one hand it is not suitable for miniaturization, and on the other hand large inductances cannot be achieved therewith.
An inductive sensor having a coil for generating a magnetic field is known from DE 103 54 694 A1. The coil is formed by two layers, between which a strip of an amorphous metal is located as a coil core. The coil windings are formed by conductive track portions arranged on the layers and by through-contactings, which run past on the coil core.
An inductive sensor which has a coil generating a magnetic field, the core of said coil being provided in an aperture in a circuit carrier, is known from DE 103 55 003 A1.